This invention relates generally to packaging systems, and more particularly to methods of making flexible packages of the kind shown in my copending earlier application further having a primary reinforced openable and resealable interlocking closure which may be further provided with hinge formations and V-notch reinforcements spaced along the length of the closure, the resealable interlocking closure having male and female parts with the primary reinforcement being formed in the female part. Several ways for forming the primary reinforcement are disclosed. Also disclosed are methods and apparatus for making such packages and closures from a continuous web of flexible film, the closures being formed during package formation at line speed.
As described in my earlier application, in the past, the methods of making reclosable flexible packages have involved either the extrusion of the locking structure along with the film extending longitudinally in the direction of film extrusion along the opposite edges of the film, or by heat sealing a separately made resealable closure structure to the package film. The first type of package formation results in packages having the reclosable feature in the consumer non-preferred position along the long edge of the package, while the second type of package formation results in packages which are expensive to make because of the need to inventory and store rolls of the separate resealable closure structure for attachment to the packaging film and the need to insure that the separately obtained packaging film and closure structure are made of compatible materials. Shown and described in my earlier application is a resealable interlocking closure of the same general kind as shown and described in this application, but which does not include the improved features of the present invention, namely, the primary reinforcement in the female part and the hinge formations and V-notch reinforcements, each of which contributes to making a superior closure.
As in the earlier application, the package and system according to the present invention also utilizes a novel converter device mounted atop or adjacent to standard packaging apparatus to form a small amount of the running packaging film into the resealable closure structure as an integral part of the film oriented in one form in the consumer desired direction extending transversely to the long dimension of the package. The converter functions with both horizontal and vertical form/fill/seal wrapping machines and with overwrap packagers, and uses diverse double sided heat seal packaging films such as polypropylene, polyester, polyvinyl chloride, high and medium density polyethylene, thermoplastic heat seal coated non-plastic films, and various film laminations.
In the previously referred to one form of the invention the package formation begins by feeding the plastic mm, as it unwinds from the storage roll, into the the converter, where the film is automatically layered by fanfolding across the entire width of the film to form a stack. Layering other than by fanfolding to form a stack may be utilized, as for example heat sealing a strip of heat sealable material to the packaging film, but fanfolding is a convenient, fast and economical method of stack forming. The number of folds will vary depending on the thermoforming properties and thickness of the particular film being used. The stacked layers are immediately edge heat sealed together widthwise of the running film forming a multilayered strip of typically one half inch width extending completely across the film width in plane with the film, the strip layers being unsecured to one another between the edge seals. Next, the multilayered strip carried by the packaging film is abraded on one surface to remove the thermoplastic heat seal coating, in one case except at one end, and in another case except at both opposite ends, and leave the remainder of that surface of the strip uncoated, the film being then passed into the package forming apparatus where the product wrapping and longitudinal package sealing takes place. After emerging from the package forming apparatus the package ends are sealed and the package resealable locking feature is formed in the stacked layers of film or in the strip which has been heat sealed to the film, with or without the hinges and the Vnotch reinforcements as desired. The entire process takes place at packaging line speed.
In another form of the invention the package formation begins by feeding the plastic film, as it unwinds from the storage roll, into the the converter, where the film is first longitudinally folded along one edge before being fanfolded as previously described. A modification of this form of the invention is provided by adding a strip of film to at least one longitudinal marginal edge of the web in lieu of edge folding, the strip being of substantially the same width as the package longitudinal seal. The point of application of the strip determines the form of the primary reinforcement of the interlocking closure.
In the foregoing described forms of the invention the reinforced resealable interlocking closures are all formed transversely to the direction of film flow. In one other form of the invention the reinforced resealable interlocking closures are formed in line with the direction of film flow along one edge of the package and may be formed in either of the two previously described ways, by fanfolding or by adding a strip of heat sealable material to the packaging film. In this form of the invention the primary reinforcement extends the full length of the female part of the resealable closure.
My earlier patent application discloses an interlocking closure similar to that of the present invention, except that in that package structure the male and female parts are reversed as compared to the present invention, and as previously noted the hinge structures and V-notch reinforcements are absent. In the present invention, the female part of all embodiments of the invention except one is formed on the face of the package where the longitudinally extending package seal is formed. This is a very significant difference, in that by so forming the female portion to include the longitudinally extending overlapped central region of the package, it includes in its structure several times the number of plies in the male part that interlocks with it, the number of additional plies being determined by the particular form of the invention utilized. In the form of the invention where the interlocking closure is along one edge of the package, the female part of the closure can also be formed with more plies than the male part to provide a reinforced interlock. These reinforcements provide a much stronger package lock which better prevents the packages from inadvertent opening. When incorporated, the V-notches provide further resistance to opening of the interlock, and the hinges provide the ability to control the shape of the package opening. Accordingly, it is a primary object of the invention to provide novel methods of making reinforced openable and resealable interlocking closures for packages.
Another object of the invention is to provide methods of making packages having novel reinforced openable and resealable interlocking closures which may be provided at intervals along their lengths with hinge structures which separate the interlocking closures into segments and control the shape of the package opening.
A further object of the invention is to provide methods of making a package having a novel reinforced openable and resealable interlocking closure which may be provided at intervals along its length with V-notch reinforcements.
An additional object of the invention is to provide methods of making a package having a novel reinforced openable and resealable interlocking closure as aforesaid in which the reinforcement is partly provided by selectably added layers of the packaging or other film.
Yet another object of the invention is to provide methods of making packages having novel reinforced openable and resealable interlocking closures as aforesaid in some of which the closure is formed transversely to the direction of packaging film flow and in others of which the closure is formed in line with the direction of packaging film flow during the packaging operation running at line speed.
A yet further object of the invention is to provide methods of making novel packages as aforesaid in which the reinforced resealable interlocking closure is integrally formed from layered together contiguous portions of the packaging film during the packaging process and does not require that additional materials be added to the packaging film to form the resealable closure, and in another form the resealable interlocking closure is formed in a heat sealable strip heat sealed to the packaging film.
A still further object of the invention is to provide methods of making novel packages as aforesaid in which the packages may be formed from a variety of packaging films such as polypropylene, polyester, polyvinyl chloride, high and medium density polyethylene, and various film laminations.
Still another object of the invention is to provide methods of making novel packages as aforesaid in which the reinforced resealable interlocking closure is integrally formed from the packaging film by reversely fanfolding the packaging film either across or orthogonal to its width to form a stack, sealing together the reversely folded stack in plane with the film, and thermoforming the sealed stack into the resealable locking feature.
A further object of the invention is to provide methods of making a package having a novel reinforced openable and resealable interlocking closure in which the resealable closure extends only partly across the package to limit the open size of the closure.